This is a paid asset, but now you can download Lightning Effect Free.
Detail this asset from Unity Store: Original Link
Lightning Effect v1.1
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Abrupt electric discharge between two points
Lightning effect. Renders lightning between two points using Linerenderer and animated texture.
Package contains 3 animations Each animation represented with 3 textures (total 9 textures):
64 tiles 4096×4096 pixels
32 tiles 2048×4096 pixels
16 tiles 2048×2048 pixels
version 1.2 material instansing + bugfixes
version 1.1 all textures are black&white.
Tiles are organized in columns. You can reduce texture size by removing one of the columns or scale whole texture down a couple of times.
Add LightningScript.cs script to the object then specify target game object and desired material.
Script will add LineRenderer in the runtime and continuously alternate between tiles and animate LineRenderer vertices.